1. Field of the Invention
This invention relates to monoazo dyestuffs for polyester fibers. More specifically, it relates to monoazo dyestuffs which dye polyester fibers in blue colors excellent in various fastness properties, in particular, light fastness, sublimation fastness, washing fastness, perspiration fastness and water fastness, and which are also excellent in heat resistance and alkali discharge printing properties.
2. Description of the Prior Art
Recently, an alkali discharge printing process has been increasingly frequently carried out as a new dyeing process for polyester fibers. The principle of the alkali discharge printing is to hydrolyze a dyestuff with alkali, thereby depriving it of its affinity to polyester fibers.
Therefore, the dyestuffs intended for that purpose contain carboxylate ester groups, hydroxyl groups etc. which have great hydrophilic properties and are easily reactive with alkali in their backbone structure. For that reason, they had a disadvantage that their moisture fastness, such as washing fastness, perspiration fastness, water fastness etc. and also heat resistance were poor. The present inventors have been intensively studying in order to develop blue dyestuffs having good alkali discharge printing properties and also having good moisture fastness and heat resistance, and finally have solved this antithetical contradiction in principle, thereby having accomplished this invention.
Although dyestuffs having structures analogous to those of this invention are known from Japanese Patent Application Laid-open No. 133457/1980, it is evident, as demonstrated by the comparison data in Table 1, that the dyestuffs of this invention are far more excellent in both moisture fastness and heat resistance as well as maintain good alkali discharge printing properties.
TABLE 1 __________________________________________________________________________ Alkali Fastness after Discharge Polyurethane Finish Printing Perspi- Heat Structural Formula Properties Washing ration Water Resistance __________________________________________________________________________ Known Dyestuff 1 ##STR2## Grade 4-5 Grade 1-2 1-2 1-2 50 Known Dyestuff 2 ##STR3## " 2 2 2 55 Known Dyestuff 3 ##STR4## " " " " 50 Dyestuff of the Invention ##STR5## " 4-5 5 4-5 95 Dyestuff of the Invention ##STR6## " 5 5 5 95 Dyestuff of the Invention ##STR7## " 4-5 5 4-5 95 __________________________________________________________________________ Notes: (1) Known Dyestuff 1, Known Dyestuff 2, and Known Dyestuff 3 All described in Japanese Patent Application Laidopen No. 133457/1980. (2) Alkali discharge printing properties A dyed cloth previously dyed with the particular dyestuff was coated with a discharge printing paste containing sodium carbonate and polyethylene glycol (average molecular weight: 400), treated with superheated steam at a temperature of 180.degree. C. for 7 minutes, then reducingly washed, an the whitness of the discharged part of the obtained dyed cloth was judged using a gray scale for staining. (3) Polyurethane finishing method Curing was conducted using a 1% solution of Hydran F24 K at 160.degree. C for 2 minutes. (4) Washing fastness A multifiber was attached to a dyed, polyurethanefinished cloth, and a washing test was conducted according to AATCC Method, Washing No. IIA; th staining of the nylon fiber of the multifiber was judged by a gray scale. (5) Perspiration fastness A dyed, polyurethanefinished cloth was tested according to JIS L0848 Method A, using a nylon cloth and a silk cloth as attached cloths, and th degree of staining of the silk cloth was judged by a gray scale. (6) Water fastness A dyed, polyurethanefinished cloth was tested according to JIS L0846 Method A, except that the attached nylon cloth was replaced by a silk cloth, and the degree of staining of the silk cloth was judged by a gray scale. (7) Heat resistance A dyestuff cake was mixed with a naphthalenesulfonic acidformaldehyde condensate, and heat treated at 130.degree. C. for an hour; the percent o the remaining dyestuff after heat treatment was determined to judge the heat resistance. ##STR8##